I have an old 440 gasser that I finally killed the engine in. From the sound of it I would guess broken rod or broken valve. What would you recommend for a replacement engine? How many HP does this little machine need? Would a 25 HP air cooled do it? It's almost 40 years old so I don't want to put a lot of money into it but I think it's worth saving. Everything else is pretty good. Thanks Mule